DOE manager bolsters NIST Color Quality Scale

Dr. James Brodrick, lighting program manager for the U.S. Department of Energy Building Technologies Program, recently highlighted the new Color Quality Scale (CQS) developed by NIST. Writing in the online newsletter Postings, Brodrick endorsed the CQS for adoption by the International Commis¬sion on Illumination (CIE) Technical Committee (TC) 1-69 as a replacement for the current standard, the Color Rendering Index (CRI). He encouraged members of the solid-state lighting community to also voice their support for the CQS.

The CQS, which was developed by PL scientists within the Optical Technology Division, more accurately describes the lighting quality of white light sources by considering chromatic discrimination and human preferences in addition to color rendering. Under the current CRI metric, it is possible for a lighting source to have a high CRI score even though the source renders objects with saturated colors poorly. The CQS approach solves these problems and is particularly beneficial for solid-state lighting manufacturers, who must simultaneously optimize light-emitting diode (LED) lighting sources for high energy efficiency and good color quality.

Brodrick wrote, “I’ve had an opportunity to visit NIST’s color laboratory and see the CQS in action, and I can tell you it fills the bill. Regardless of the type of light source, the CQS represents the color rendering qualities of white light more accurately than the CRI and is a far better predictor for colors that have a high red content, such as skin color and wood finishes—which is one of the CRI’s major weaknesses.”

TC 1-69 will soon be making its recommendation on a new metric for evaluating the color rendition of white light sources. A metric that is very similar to the CRI is currently receiving strong support by some committee members, but Brodrick believes the CQS better overcomes the shortcomings of the CRI.

Brodrick’s endorsement of NIST’s CQS has been the subject of several news pieces in the past month with articles appearing in LEDs Magazine and OptoIQ. For further reading, see Brodrick’s article.